1. Field of the Invention
The present invention relates to an apparatus and method of displaying a display power management signaling (DPMS) state using an on-screen display (OSD) integrated circuit (IC) in a display device. Specifically, this invention is a DPMS state display apparatus and method for displaying the present state of DPMS using an OSD IC when a signal is abnormally input to a display device, or a signal cable is detached.
2. Discussion of Related Art
Generally, a display device comprises control means for reducing power consumption. In one approach, the control means may be implemented by a DPMS, proposed by Video Electronics Standard Association (VESA) in U.S.A. The DPMS functions to manage power of a display device, which is one of the peripheral devices of a computer, according to a used state of the computer to save the power. It is well known that the DPMS power supply modes may be classified into a normal mode, a standby mode, a suspend mode and a power-off mode. Power management in a computer is described in, for example: U.S. Pat. No. 5,586,333 to Chun-Geun Choi, et al., entitled, Method And Control Apparatus For General Power Management Signal Of Computer Peripheral Equipment IN A Computer System; U.S. Pat. No. 5,555,032 to Yung-Keng Kung entitled Integrated Circuit For Economizing Power Consumption Of A Monitor By Using Two Reference Values For Discriminating The Input Signal; U.S. Pat. No. 5,428,790 to Leroy D. Harper, et al., entitled, Computer Power Management System; U.S. Pat. No. 5,396,635 to Henry T. Fung, entitled, Power Conservation Apparatus Having Multiple Power Reduction Levels Dependent Upon The Activity Of the Computer System; and U.S. Pat. No. 5,389,952 to Dan Kikinis entitled Low-Power-Consumption Monitor Standby System.
In conformity with VESA, the computer selectively supplies or blocks horizontal and vertical synchronous signals to the display device according to the computer's state, and the display device manages power according to the presence of the horizontal and vertical synchronous signals from the computer.
The power management states are classified into an on state, a stand-by state, a suspend state and a power off state. Both the horizontal and vertical synchronous signals are applied in the on state, and only the vertical synchronous signal is applied in the stand-by state. Only the horizontal synchronous signal is applied in the suspend state, and neither the horizontal nor vertical synchronous, signal are applied in the power off state. The DPMS state converts from an on mode to a stand-by mode, a suspend mode, and an off mode in sequence, according to a time lapse corresponding to the lack of use of the computer system. I have determined that the user should be notified of the current DPMS state. I have considered that the use of color light emitting diodes (LEDs) installed on a display device, or blinking LEDs would result in a problem that a user must be well acquainted with LED states through a guide program provided by a display device provider in order to recognize the displayed DPMS state.
Additionally, I have determined that when a signal cable for transmitting a signal output by a main body is not connected, the DPMS state must be converted to an off mode to minimize power consumption. However, the power necessary for a normal operation must be applied to a display device in order to display a message for warning or informing a user of the present state by driving an OSD. There would then be a problem that power is consumed while the OSD is being driven.